GB916324A - Improvements in or relating to nuclear reactors - Google Patents

Abstract

916,324. Controlling reactors. ROLLSROYCE Ltd. April 27, 1959 [April 25, 1958], No. 13295/58. Class 39 (4). A nuclear reactor is controlled by varying the level of an absorbing or moderating liquid in tubes extending into the moderator. Fig. 1 shows a reactor with heavy water moderator in a tank 10. The tank contains tubes 21, open at the bottom, in which the water level is controlled by the pressure of the gas supplied through pipes 23. The gas pressure is controlled to keep the water level at a constant position in each tube. The tank 10 is connected to a dump tank 15 in which a high He pressure P 0 is maintained. This pressure is supplied to valves V 1 which pass on to valves V 2 a pressure P R equivalent to the pressure head of a column of moderator of the desired length. A reference pressure P 4 is derived from a plane grid of tubes 38 below the reactor. P 4 -P R is measured in V 2 and the result used to control the supply of gas from the dump tank to the tubes 21, so that the length of the moderator column is kept constant regardless of pressure variations or tilting of the reactor. Valves V 1 are controlled by a weight and a lever arm which may be adjusted to alter the pressure P R and hence the moderator level. Each tube 21 may have its own control system.